Carcinoma of the breast is one of the most common cancers in women. Man's search for qualitative differences between normal and malignant mammary epithelial cells has been complicated by the fact that malignant breast cancers contain large numbers of fibroblasts, endothelial cells, lymphocytes, and blood cells in addition to the malignant mammary epithelial cells. Similarly, the normal precursor of the malignant mammary epithelial cell is associated with and diluted by many other kinds of cells. With methods which we have used previously for the disaggregation of tissues and for the purification of cells from many different kinds of tissues including colonic cancer, prostatic cancer, and Hodgkin's disease tumor, we shall develop methods for the purification of individual kinds of cells from breast cancer, breasts with other pathologic lesions, and breasts which are free of disease. Our separations of cells from breast cancers and breasts without cancer will be accomplished by sedimentation in the isokinetic gradient (developed in our laboratory) and by the Zeiller-Hannig type of free-flow electrophoresis as employed in our laboratory previously. After determining the optimal conditions for the disaggregation of tissues and for the purification of cells from these tissues, we shall characterize the cells in detail and attempt to grow them in culture. The tumorigenicity of the purified cells will be tested by heterologous transplantation. After the period of support requested, we expect that new proposals will be submitted for the support of biochemical studies of epithelial cells from breast cancers and breasts without cancer. Should we find significant biochemical predictors of the biological behavior of breast cancer in later years, we shall be assisted in expanding our studies by collaboration with a large state-wide, funded prospective study of the treatment of breast cancer administered from the University of Alabama Medical Center.